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Finding the Fourth Proportional to 720.86, 1,081.44 and 391.77

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Solution

The fourth proportional to 720.86, 1,081.44 and 391.77 is: 587.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    720.86 : 1,081.44 = 391.77 : x
  2. Step 2: Convert to fraction form
    720.86/1,081.44 = 391.77/x
  3. Step 3: Cross multiply
    720.86x = 1,081.44 × 391.77
  4. Step 4: Simplify right side
    720.86x = 423,675.75
  5. Step 5: Solve for x
    x = 423,675.75/720.86
  6. Step 6: Final answer
    x = 587.74

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.